In general, a wheel for a vehicle, as shown in FIGS. 1 and 2, includes a rim 10 supporting a tire and a disc 20 that is integrally fitted to the rim 10 and is to be connected to an axle shaft.
In a type of wheel illustrated in FIG. 2, the disc 20 is press-fitted inside the rim 10 in the direction of an arrow shown in FIG. 2. The disc 20 is then integrated to the rim 10 by welding, in which the inner circumference of rim 10 is fixed to the outer circumference of disc 20.
The disc 20 includes a hub hole 21 at the center portion, in which the hub hole 21 is defined by a cylindrical flange 22 protruding to one side of the disc 20. A hub cap (not shown in FIG. 1 or 2) is to cover the hole 21 and a portion of the disc 20.
The disc 20 includes a plurality of vent holes 23 that are circumferentially arranged at radially predetermined positions from the center of hub hole 21. The vent holes 23 are to let heat from braking discharge to outside.
In typical production of the disc 20, burrs 24 are formed on the edges of vent holes 23. Also, in typical production of the wheel, the disc 20 is forcibly press-fitted into the rim 10, without removing the burrs 24.
Therefore, the inside of rim 10 can be damaged by burrs 24, when disc 20 with burrs 24 is forcibly press-fitted into the rim 10 in the direction of the arrow shown in FIG. 2.
Although it is possible to remove the burrs 24 by a post-machining, a large amount of time and cost would be required for the post-machining.
Further, once the rim 10 and disc 20 have been assembled together, the assembly is typically washed with water, and then water is removed and the assembly is coated after the washing. However, during the washing, some water may be kept between the inner circumference of the rim 10 and the outer circumference of the disc 20, and the water may not be completely removed, even if the water is removed by injecting high-pressure air (Reference character M1 in FIG. 1 indicates the portion where water collects again after the process of removing water). Thus, when coating is performed without completely removing water, spots may be created in the resulting coating.
The foregoing discussion is solely to provide background information, and does not and should not constitute admission of prior art.